Conventional private branch exchange (PBX) telephone systems often incorporate features which limit the capabilities of certain extensions. For example, certain extensions may be set up to block incoming calls, while others are set to prevent outgoing calls from being made therefrom. Other limitations include allowing outgoing calls, but preventing the caller from connecting to certain area codes and prefixes. While these phone systems thus limit the connection capabilities of extensions connected thereto, there is no time limit to the calls made.
Telephone calls are often made from public telephone booths and the like wherein the calling telephone is disconnected at the central station after a time expires, but not locally in private branch exchanges. Moreover, such telephones are disconnected in dependence on the expiration of purchased time, which typically depends on the location of the number dialed, and not on a fixed, preprogrammed basis independent of these other factors.
Nevertheless, in certain environments such as schools, students often need access to a telephone, for example to call home to arrange a ride. Schools often provide one or more telephone extensions for this purpose. However, if a significant number of students need access to such telephones at approximately the same time, for example following an after-school activity, the students are required to wait their turn until a telephone becomes available. However, without supervision, a single student is able to tie-up one of the telephones provided for an excessive amount of time, inconveniencing other students or otherwise abusing telephone privileges.